Electric control device

ABSTRACT

An electric control device of the overload relay type characterized by a plurality of pole units, relatively movable contacts, means for actuating the contacts between open and closed positions and being biased in the closed position, the means comprising a cam shaft rotatable between first and second positions corresponding respectively to the closed and open positions of the contacts and being biased in the first position, overload current responsive means associated with each of the pole units for actuating the cam shaft to the second position when an overload occurs in at least one of the pole units, and manual reset means operatively connected to the cam shaft for rotating a cam shaft to the first position.

United States Patent Anderson et al.

1451 Oct. 15,1974

[ ELECTRIC CONTROL DEVICE Primar' Examiner l. D. Miller [75] Inventors: Paul T. Anderson; James B.

Asszstant ExammerFred E. Bell Ramsey both of Beaver Attorney, Agent, or Firm-L. P. Johns [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa, [57] ABSTRACT 22] il d; M 1 1973 An electric control device of the overload relay type characterized by a plurality of pole units, relatively [211 Appl' 337,241 movable contacts, means for actuating the contacts between open and closed positions and being biased in 52 us. c1 337/151, 337/150, 337/154, the elesed Petition, the means comprising 11 earn Shaft 337/40 rotatable between first and second positions corre- 51 1m. (:1. H0lh 71/20 Spending respectively to the elesed and p Positions [58] Field of Search 337/150, 151, 153, 154, of the eehteets and being biased in the first Position, 337/155 406 410 overload current responsive means associated with each of the pole units for actuating the cam shaft to [56] References Cited the second position when an overload occurs in at UNITED STATES PATENTS least one of the pole units, and manual reset means 3 179 757 4/1965 B d b 337/152 X operatively connected to the cam shaft for rotating a ran en erg t 3,223,803 12/1965 Walters 337 153 x cm Shaft to the first 'i' 3,258,566 6/1966 Arneber et al 337/151 6 Claims, 16 Drawing Figures e2 e0 1 9O I 5 PAH-M50021 1 51974 SHEET 2 OF 5 2. I... LLLLLLL-FF SHEET a 0? 5 V/ mM mmjm FIG. l5

PATENIED HEY I 51974 FIG. l4

ELECTRIC CONTROL DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electric control device and more particularly it pertains to a thermally responsive overload relay.

2. Description of the Prior Art Overload relays of the type used to protect an electric motor are known in the art. Most of such relays have been subject to such problems as poor shock characteristics, unreliable resetting mechanism, and mediocre trip characteristics. Indeed, prior existing overload relays having reliability and endurance often have been disproportionately costly and not susceptible to replacement of worn out parts.

SUMMARY OF THE INVENTION In accordance with this invention, it has been found that the foregoing problems may be overcome by providing an electric control device comprising a plurality of pole units, a stationary contact. a movable contact, a movable contact mounting member biasing the contacts in the closed position, means for actuating the contact for the open position and comprising a cam shaft rotatable between first and second positions corresponding respectively to the closed and open positions of the contacts and being biased in the first position, the cam shaft comprising an elongated rotatable shaft anda first arm extending laterally of the shaft for each pole unit, means responsive to an overload current and associated with each of the pole units for actuating the cam shaft to the second position when an overload current occurs in at least one of the pole units and said means being separately operable with each arm, the contact actuating means also comprising a lever associated with the cam shaft for moving the movable contact mounting member to the open position when an overload current occurs, and manual reset means operatively connected to the cam shaft for rotating the cam shaft to the first position.

The advantage of the device of this invention is the provision of an overload relay that includes improved trip characteristics, replaceable thermally responsive overload current means having improved thermal endurance, and pole units having relatively the same ratmgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of the device of this invention;

FIG. 2 is a plan view of the device shown in FIG. 1',

FIG. 3 is a right end view of the device shown in FIG.

FIG. 4 is a plan view of the lower portion of the device with the upper portion removed;

FIG. 5 is a perspective view of the cam shaft;

FIG. 6 is a perspective view of the reset rod;

FIG. 7 is a perspective view of the interlock slide;

FIG. 8 is a perspective view of the trip arm;

FIG. 9 is a perspective view with a portion broken away of the solder pot ratchet and latch spring assembl FIG. 10 is a vertical sectional view taken on the line X-X of FIG. 1;

FIG. 1] is a vertical sectional view of the parts shown in FIG. 10 in alternate positions;

FIG. 12 is a vertical sectional view taken on the line XII-XII of FIG. 1;

FIG. 13 is a vertical sectional view similar to that of FIG. 12 and showing the parts in alternate positions;

FIG. 14 is a vertical sectional view similar to that of FIG. 12 and showing the several part in alternate positions;

FIG. 15 is a vertical sectional view taken on the line XVXV of FIG. 2; and

FIG. 16 is a vertical sectional view similar to that of FIG. 15 and showing the parts in alternate positions.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGS. 1, 2, and 3 a relay is generally indicated at 10 and it comprises an upper housing 12 and a lower housing 14, which housings are held together at a parting line 16 by two screws 18 (FIGS. 1 and 3) located at diagonally opposite corners. The upper housing 12, being composed of an electrically insulating material, supports three longitudinally spaced transversely extending terminals 20, 22, and 24 of similar construction. The terminal 20 comprises a pair of spaced conductor straps 20a and 20b, a U-shaped interconnecting heater strap 20c (FIG. 3), terminal plates 20c, and terminal screws 20f. Spaced screws 20g on opposite sides of the interconnecting heater strap 20c hold the strap in electrical contact with the conductor straps 20a and 20b. Each of the terminals 22 and 24 comprise corresponding parts which are identified by similar alphabetical suffixes. Each pair of adjacent terminals 20, 22, and 24 are separated by insulating barrier portions 26 and 28 respectively which are integral parts of the upper housing 12.

As shown more particularly in FIGS. 10 and 11 the upper housing 12 is a box-like member forming a chamber 30 in which the operating parts of the relay 10 are disposed. One of the parts comprises thermally controlled means or solder pot" 32 which extends through an opening 34 in the top surface of the upper housing 12 where it is secured by a screw 36 (FIG. 2). Each pole of the relay includes a solder pot 32 which as shown for the terminal 20 is associated with the U- shaped interconnecting heater strap 200. The solder pot 32 is similar to the thermally controlled means disclosed in US. Pat. No. Re 20,094 issued to G. O. Wilmes et al., dated Sept. 1, I936.

More particularly, the solder pot 32 is a tubular member 38 extending upwardly from a supporting base 40. A rotatable shaft 42 is journally mounted within the member 38 and is provided with a ratchet wheel 44 that is engaged by a pawl 46. The upper end of the shaft 42 includes a cup portion 48 in which a body 50 of solder is contained. The upper portion of the body 50 of solder overflows the cup portion 48 and is in contact with the inner surface of the tubular member 38. When the body 50 of solder is solid, the shaft 42 is frozen in place and the ratchet wheel 44 will not rotate. However, when the body 50 of solder is heated sufficiently to melt, the ratchet wheel 44 is freely rotatable. When a normal current passes through one of the terminals 20, 22, 24 the body 50 of solder is solid. However, when an overload current such as a motor overcurrent occurs, the U-shaped interconnecting heater strap 20c is heated sufficiently to melt the body 50 of solder,

whereby the ratchet wheel 44 is free to rotate. Thus, the interconnecting strap 20c serves as a heater for the solder pot 32. In addition to the foregoing, a reset rod 52 (FIG. 6) is mounted in an aperture 54 in the upper housing 12 where the rod is normally disposed in an uppermost position by a compression spring 56. The rod 52 is pushed downward manually in a manner to be described hereinbelow when it is desirable to reset the relay.

The lower housing 14, being composed of electrically insulating material, is a box-like member (FIGS. 10-15) which includes a chamber 58 in which a number of movable parts are disposed including a cam shaft 60 (FIG. a trip arm 62 (FIG. 8), and an interlock slide 64 (FIG. 7). As shown more particularly in FIG. 5, the cam shaft 60 includes opposite end portions, three upright arms 66, a reset arm 68, a trip arm 70, circular fins 72 and 74, and a web 76. The cam shaft 60 is located within the chamber 58 of the lower housing 14 where the end portions are rotatably seated in similar notches 78 (FIG. 4), whereby the cam shaft is free to rotate slightly clockwise and counterclockwise in response to various forces applied thereto.

As shown in FIG. 10, the cam shaft 60 is supported in position by a transverse portion 80 of the pawl 46 which portion is retained in place by a bolt 82 which is secured to the lower housing 14 by a nut 84. All of the pawls 46 include similar transverse portions 80 which are secured in place by similar bolts 82 and nuts 84. As shown in FIG. 4, the fin 72 is disposed between the leftmost pawl 46 and a spring contact arm 86 (FIG. Likewise, a fin 74 is disposed between the intermediate pawl 46 and a spring contact arm 88. The fins 72 and 74 provide insulation against electrical creepage between the indicated parts.

As shown more particularly in FIGS. 1 and 10 a pair of vertically disposed terminal straps 90 and 92 are disposed on the outer surface of the lower housing 14 where they are retained in place by screws 94 and 96. The terminal straps are provided with similar terminal screws 98 which are connected to leads (not shown) that are electrically connected to a suitable alarm device such as a hell or light to indicate when the relay is in the open condition as set forth hereinbelow. The spring contact arm 86 is connected to the inner end of the upper terminal strap 90 by the screw 94. The lower end of the spring contact arm 86 is provided with a contact 100 which cooperates with a contact 102 at the inner end of the terminal strap 92. Thus, when the cam shaft 60 is rotated counterclockwise, the web 76 moves the contact 100 from the normally open position (FIG. 10) to the closed position (FIG. 11).

In addition, as shown in FIGS. 1 and 15, a'pair of terminal straps 104 and 106 are mounted by similar screws 108 on the outer surface of the lower housing 14 and are provided with similar terminal screws 110 for connection by suitable leads (not shown) to a coil of an electromagnetic contactor of the type shown in US. Pat. No. 3,339,161 issued Aug. 29, 1967 to J. P. Conner et al. assigned to the same assignee as this application. The inner end of the strap 104 is provided with a contact 112 which in the normally closed position engages a contact 114 at the upper end of the spring contact arm 88 which arm is electrically connected to the strap 106 and secured in place by the screw 108.

In the normally closed position of the contacts 112 and 114, the cam shaft 60 is in the position shown in FIGS. 4, 12, and 15, whereby the upright arms 66 are out of contact with the pawls 46. The cam shaft 60 is maintained in that position by a compression spring 116 (FIG. 15) and the spring contact arm 86 (FIG. 10),

that is the spring 116 urges the trip arm in a clockwise direction and the spring contact arm 86 urges the web 76 in a clockwise direction. Under normal operating conditions the body 50 of solder solid is solid, the contacts 112 and 114 are normally closed and the contacts and 102 are normally open.

When an overload occurs on a motor or other device to which the terminals 20, 22, and 23 are electrically connected, the body 50 of solder is heated above the melting point. The pawl 46 is an elongated L-shaped member secured in place as indicated above by the bolt 82 and composed of a spring-type material having a normal position shown by the solid line position 46 of FIG. 11. When the body 50 of solder is solid, the pawl 46 is retained by the teeth of the ratchet wheel 44 in the position shown in FIG. 10, or the broken line position 46 of FIG. 11. When the body 50 of solder melts, the force of the pawl 46 rotates the ratchet wheel 44 in the direction of the arrow 118 and the pawl 46 moves to its normal position and rotates the upright arm 66 counterclockwise in the direction of the arrow 120 (FIG. 11) from the position of FIG. 10 to the position of FIG. 11. Although one or more of the solder pots 32 may be influenced by any overload occurring in the phases leading from the load such as a motor, the force of only one pawl 46 is sufficient to move the cam shaft 60 to the position shown in FIG. 11, thereby opening the contacts 112 and 114.

When the cam shaft 60 is rotated counterclockwise, a lever portion 122 (FIG. 5), which is an integral part of the cam shaft 60, moves counterclockwise from a position shown in FIG. 12 to that shown in FIG. 13 and thereby moves the trip arm 62 in a clockwise direction. The trip arm 62 is pivotally mounted at 124 at its lower end in the base of the lower housing 14. At its upper end the trip arm 62 is provided with a projection 126 (FIG. 8) which as shown in FIGS. 4 and 12 engages the spring contact arm 88 to provide a single point contact therewith.

When the relay trips; that is, when the body 50 of solder melts and the cam shaft 60 rotates counterclockwise to open the normally closed contacts 112 and 114, the interlock slide 64 moves to the right in the direction of the arrow 128 (FIG. 13), thereby moving a projection 130 on the slide out of the path of downward movement of a portion 132 of the reset rod 52. The interlock slide 64 is normally held in the retracted position of FIG. 12 by the upper end of the trip arm 62 which has a projection 134 for providing a single point contact with the interlock slide. When the trip arm 62 is rotated clockwise to the position of FIG. 13, a compression spring 136 urges the slide 64 to follow the upper end of the arm, whereby the projection 130 moves out of the path of travel of the portion 132 of the reset rod 52.

After the body 50 of solder solidifies, the relay 10 can be reset by depressing the reset rod 52 to move the lower end portion 138 (FIG. 6) against the arm 68 (FIG. 14) and to rotate the cam shaft clockwise in the direction of the arrow 140 and against the pawl 46, thereby relatching the pawl on the ratchet wheel 44.

Upon release of the reset rod 52, the spring 56 returns the rod to the upper position as shown in FIG. 13 and if the body 50 of solder is not yet solidified the pawl 46 will rotate the ratchet wheel 44 and move against the arm 66 of the cam shaft 60 in the manner set forth above, thereby continuing to retain the contacts 112 and 114 in the open position.

When the reset rod 52 is depressed to the position shown in FIG. 14, the interlock slide 64 cannot return to the latch position until the rod is released. Thus, the interlock slide 64 remains in the position of FIG. 14 during the reset cycle and retains the contacts 1 12 and 114 out of contact even though the arm 68 of the cam shaft is rotated and the pawl 46 is reset on the ratchet wheel 44. Accordingly, if the body 50 of solder is not resolidified, the relay will not latch and the slide 64 remains in the position of FIG. 14. Thus, the trip-free feature is maintained by a proper spring loading and interlocking of the reset rod 52 and the slide 64.

A portion 142 of the slide 64 projects through an opening 144 of the lower housing 14 to give a visual indication that the relay remains in the trip position. Manifestly, when the body 50 of solder is resolidified and the pawl 46 is relatched on the ratchet wheel 44, the cam shaft 60 returns to the latched position (FIG. and upon release of the reset rod 52, the spring 56 returns the rod to the uppermost position and the interlock slide 64 returns to the retracted position (FIG. 12) in response to the pressure applied by the spring control arm 88 and the contacts 112 and 114 are again in the normally closed position.

In addition to the foregoing, the relay 10 is provided with means for testing the relay after initial assembly and after each resetting operation. When the relay 10 is tripped, the contacts 112 and 114 may be welded together due to a short circuit current. For that reason, a hand trip means is preferably provided to test whether the normally closed contacts 112 and 114 may be opened as well as whether the normally open contacts 100 and 102 may be closed. The manual trip means include a rod 146 which is vertically movable within a slot 148 in the upper housing 12. The lower end of the rod 146 is disposed on the trip arm 70 and the upper end is recessed within the top end of the slot 148 so that it is not readily available for use. Upon insertion of a tool such as a screwdriver into the slot 148, the rod 146 may be depressed in the direction of the arrow 150, thereby causing the cam shaft 60 to rotate counterclockwise and open the contacts 112 and 114 at the same time the portion 142 of the slide 64 appears in the notch 144. Upon release of the rod 146 the cam shaft 60 returns from the unlatched position (FIG. 16) to the latched position (FIG. In that manner, the relay 10 may be tested after assembly without removing one of the solder pots 32.

Accordingly, the relay of this invention solves problems inherent in relays of the solder pot type of prior construction and in addition provides advantages including a more reliable control circuit and a shockproof relay. Finally, the relay of this invention provides more force for manual resetting thereby providing more reliable engagement between the contacts.

What is claimed is:

1. An electric control device comprising a plurality of pole units, a stationary contact, a movable contact, a movable contact mounting member biasing the contacts in a closed position, means for actuating the contacts to the open position and comprising a cam shaft having a first arm for each pole unit and rotatable between latched and unlatched positions corresponding respectively to the closed and open positions of the contacts and being biased in the latched position, means responsive to an overload current and associated with each of the pole units for actuating at least one first arm of the cam shaft to the unlatched position when an electric overload occurs in at least one of the pole units, reset means operatively connected to the cam shaft for rotating the cam shaft to the latched position, the reset means comprising a manually operated reset rod movable between retracted and resetting positions, the cam shaft having a second arm in the path of movement of the reset rod, and the reset rod being biased in the retracted position and movable against the second arm to rotate the cam shaft in one direction opposite that of the first arm.

2. The electric contact device of claim 1 in which the cam shaft is contained within a housing, and the reset rod extends through a first opening in the housing.

3. The electric contact device of claim 1 in which an interlock member is movably mounted into and out of the path of movement of the reset rod, and the interlock member being biased in said path of movement when the cam shaft is in the latched position.

4. The electric contact device of claim 3 in which the contact actuating means comprises a lever associated with the cam shaft for moving the movable contact mounting member to the open position when an overload current occurs, the lever being biased to the contact closed position and being disposed in the path of movement of the interlock member, and the interlock member being movable by the lever into the path of movement of the reset rod when the lever is in the contact closed position.

5. The electric contact device of claim 4 in which the interlock member maintains the lever in the contact open position when the reset rod is in the reset position.

the direction opposite that of the second arm. 

1. An electric control device comprising a plurality of pole units, a stationary contact, a movable contact, a movable contact mounting member biasing the contacts in a closed position, means for actuating the contacts to the open position and comprising a cam shaft having a first arm for each pole unit and rotatable between latched and unlatched positions corresponding respectively to the closed and open positions of the contacts and being biased in the latched position, means responsive to an overload current and associated with each of the pole units for actuating at least one first arm of the cam shaft to the unlatched position when an electric overload occurs in at least one of the pole units, reset means operatively connected to the cam shaft for rotating the cam shaft to the latched position, the reset means comprising a manually operated reset rod movable between retracted and resetting positions, the cam shaft having a second arm in the path of movement of the reset rod, and the reset rod being biased in the retracted position and movable against the second arm to rotate the cam shaft in one direction opposite that of the first arm.
 2. The electric contact device of claim 1 in which the cam shaft is contained within a housing, and the reset rod extends through a first opening in the housing.
 3. The electric contact device of claim 1 in which an interlock member is movably mounted into and out of the path of movement of the reset rod, and the interlock member being biased in said path of movement when the cam shaft is in the latched position.
 4. The electric contact device of claim 3 in which the contact actuating means comprises a lever associated with the cam shaft for moving the movable contact mounting member to the open position when an overload current occurs, the lever being biased to the contact closed position and being disposed in the path of movement of the interlock member, and the interlock member being movable by the lever into the path of movement of the reset rod when the lever is in the contact closed position.
 5. The electric coNtact device of claim 4 in which the interlock member maintains the lever in the contact open position when the reset rod is in the reset position.
 6. The electric contact device of claim 1 in which the cam shaft includes a third arm, a manual test rod engagable with the third arm for rotating the cam shaft in the direction opposite that of the second arm. 